Elevator call circuit

ABSTRACT

A control system for elevators or the like wherein the elevator call button generates a first signal which is in turn sensed by the control circuit. The control circuit then provides a second signal of greater duration than the first. The second signal is utilized to produce energization of a relay which in turn controls the operation of the elevator motor and related equipment. A threshold device prevents operation of the relay when the first signal is below a threshold level so as to prevent accidental operation of the elevator by low level spurious signals. All of the control circuitry may be positioned remote from the signal generator in a safe environment. Additionally, short circuiting of the leads from the signal generator will not initiate operation of the elevator.

United States Patent 1191 v y 1111 3,774,728 1451 Nov; 27, 1973 "Metzleret al;

ELEVATOR CALL CIRCUIT Assignee: Guardian Electric Manufacturing flqmynytchieasa l'lflQlS.

Filed:

Primary ExaminerBemard A. Gilheany Assistant Examiner-W. E. Duncanson,Jr. Att0meyA. W. Molinare et al.

[57] ABSTRACT A control system for elevators or the like wherein theelevator call button generates a first signal which is in turn sensed bythe control circuit. The control circuit May 10, 1972 then provides asecond signal of greater duration than the first. The second signal isutilized to produce ener- [21] Appl' N 252338 gization of a relay whichin turn controls the operation of the elevator motor and relatedequipment. A [52] US. Cl 187/29 R threshold device prevents operation ofthe relay when 1 [51] Int. Cl B66b 1/46 the first signal is below athreshold level so as to pre- [58] Field of Search 317/141, 148.5, 154;vent accidental operation of the elevator by low level 307/267; 187/29spurious signals. All of the control circuitry may be positioned remotefrom the signal generator in a safe [56] 7 References Cited environment.Additionally, short circuiting of the UN E STATES PATENTS leads from thesignal generator will not initiate opera- 3,473,o50 10/1969 Groom307/267 the elevator- 3,602,771 8/1971 Walstad et al. 317 154 x 19Claims, 2 Drawing Figures 3,571,626 3/1971 Reif 307/267 X 3,504,2363/1970 Miyagawa et al.. 317/1485 volved is to be consideredtypical eventhough the following specification is in the context of this elevatortype application.

Generally, an elevator control system utilizes push buttons arranged ateach floor. Upon depression of the push button, an electric switchingcircuit is completed and a controlsignal isfed into a relay matrix. Thisrelay matrix in' turn'operates to sendthe elevator to the appropriatefloor. This system'and similar systems which provide for makingacircuitupon operation of a button or the like have beenrefine'd and nowarejhighly sophisticated toprovide'the users of the elevator with promptand fast service. I

-However, elevators utilizing this type of control cir- J cuitry have aninherent disadvantage. This disadvan tage becomesapparentduring-emergencies such as fires. In such situations; the hightemperature due to I a firemay cause theleads associated withthe pushbutton to short. Consequently, anyone utilizing an elevator as an escaperoute ,may have-the cab of the elevator called to the floor upon whichthe fire is raging. This has in fact been the case in numerouscircumstances. Thus, it is desirable to provide an elevator call systemwhich will avoid such tragic happenings.

SUMMARYYOFA THE INVENTION In aprincipal aspect, the present inventioncomprises a control system wherein a signal generator in a circuit isconnectedto a threshold device and to an energy storing circuit so-thatupon providing a signal which is indicative ofa command, the threshold.device will provide an-outputto a command relay arrangement. Thisoutput for'the command relay arrangement will in turn closea circuitassociated with operation of the con- 3 trolled device. Because thecontrol system requires the will be made drawing cornprised 5f thefollowing? FIGURES; a v

FIG. 1 is a schematiclayoutof an entire control system as utilized foran elevator. call system; and I FIG. 2 is a circuit diagram of a singlecall station as contemplated by the present invention.

DESCRIPTION OF TI-IE PREFERRED EMBODIMENT Referring first to FIG. 1,there is illnstrated schematically the arrangement of the presentinvention as would be utilized for an elevatorcall circuit. A pluralityof push buttons 10-13 would be arranged in serial order on floors lthrough-n in a desired building. The push button would be a pulse signalgenerator device. Atypical exampleof sucha device is disclosedin the nowpending application of Britton et al Ser. No. 170,729

filed Aug. 11, 197.1. Such a device includes a coil with twoileadsextending therefrom. Depression of the push button drives a core throughthe coil thereby generat-'- ing a pulse in the coil and through theleads. These leads as at leads 1 4-17 would all be connected throughthe'control circuitry at some remote station 18. In this manner, thestation 18 could be protected against first and other dangers.Additionally, the station 18 could be maintainedat a central locationfor ease of repair and access for maintenance. Ancillary to the station18 would be a series of indicator lights at 19. Typically, suchindicator lights would show, whether a particular set of leads 14-17were functioning correctly. Outputs 20-,23 from a station 18 would'connectwith a relay matrix for controlling elevator motors, brakes andthe like.

That is, all of the leads 20-23 would be connected with a control matrixfor one or'more elevators.

In FIG. 2, there isillustrated a circuit diagram associated with thecontrol mechanism or system of the invention as provided atone controlstation, for example, the first-floor in an elevator system. Thus, likeparts are correspondingly labeled in FIG. 2. Note that the lead 14 isnow identified as leads 14a and 14b since this is a two wire system.Also, outp ut lead 20 is now identified asleads'20a and 20b.

generation of a first signal orv pulse before the control operation isinitiated, the control circuitry cannot-be activated by the opencircuiting or short circuiting of the input leads'to the controlcircuitry. Thus, aihigh temperature fusion of the lead wires to thesignal generator will not cause a malfunction of the control system thatcould possibly lead to disasterous'results. I

It is thus an object of the present invention to provide an improvedcontrol system;

It is a further object of the present invention to pro- I videanimproved control system wherein a pulse signal is utilized to initiateoperations of the control system.

Still another object of the present invention is to provide a safe andeconomical, control systemwhich can- I not accidentally be activated toprovide an'unwanted control signal.

' These and other objects,-advantages and features of the presentinvention will be set forth in greater detail in the description whichfollows.

BRIEF DESCRIPTION OF THE DRAWING In the detailed description whichfollows, reference The pulsegenerator l0'provides. a firstsignal inputvia a coil 24 to the circuit comprised of three stages each stage beingassociated with a separate transistor 26, 28 and 30. The stage oftransistor 26 provides a high impedance input circuit to keeptransmission line losses to a minimum. The stage of transistor 28 actsas a pulse stretcher. The stage of transistor 30 acts as the driver foran electromechanical load. Details of operation are as follows:

The pulsegenerator 10 via coil 24 feeds a positive going pulse or firstsignal through a diode 32' into the relatively high input impedance oftransistor 26 which is connected as an emitter follower. Diode 32 blocksany negative going pulse generated by the pulse generator 10. Thepositive pulse on the base of transistor 26 causes it to conductcharging capacitor 34. Inthe circuit shown, with compound values as setforth below, capacitor 34 is fully charged in approximately Imillisecond.

The charging of capacitor 34 causes conduction in transistor 28 which,in turn, causes conduction in transistor 30, thus energizing a relay 36.Capacitor 34 discharges supplying a second signal of greater durationthan the'first signal through the high impedance input 'of transistor28. The slow discharge of capacitor 34 in 34 and resistor 38. The relay36vis first energized on conduction of transistor 30. After initialenergization in this manner, the relay 36 latches itself in through itsnormally open contacts 40 and the transistor 30 terminates conduction.Normally open contacts 42 of relay 36 performthe switching function tothe load via leads 20a and 20b. Relay 36 remains latched throughcontacts 40 until released by switch 44 in series with con-- tacts 40.In an elevator control circuit, the load would be the elevator motor ormotor controller and the release switch 44 would provide a positionfeedback signal as switch 44 became operated by the elevator car uponarrival near its floor destination.

Aresistor 46 is providedto present a lower impedance toxthe pulse.generator than the input impedance of transistor 26, thereby reducingthe amplitude of various transient noise pulses which would be picked upon the transmission line and presented to the base of transistor 26.Capacitor 48 provides a by-pass for high frequency transients whichmight otherwise trigger the device.Resistors 50 and 52 are currentlimiters for transistors 26 and 28 respectively, and prevent anyspurious surges from damaging the transistors. Resistor 54 provides thelow impedance path to charging capacitor 34 and in conjunction withtransistor 26 provides the high impedance input to the system.

Resistor 38 is provided to assure that capacitor 34 dischargescompletely between operations. Resistor 58, in conjunction withtransistor 28 provides the high impedance discharge path for capacitor34 and thus provides the effect of pulse stretching. Resistor 60 anddiodes 62 and 64 provide reverse bias on transistor thus providing athreshold device. Since the voltage at base of transistor 30 must begreater than the bias level at the emitter of transistor 30, there isafforded more protection against accidental activation of the relay bylow level spurious signals. Resistor 66 provides a base return fortransistor 30.

Diodes 65-68 form a diode bridge full wave rectifier for 30 voltunfiltered direct current for the operation of the relay 36. Half 'ofthe supply is filtered by a capacitor 70 and is used as the power sourcefor transistors 26 and28. Diode 72 is used to shunt the inductive ef-Element Rating :1. Resistors Value 46 15 K 0 54 l K I). 50 V 270 Q 381.0 Meg Q 52 270 0. 58 1.5 K 0 66 10.0 K 0 60 15 K O.

b. Capacitors 48 0.01 microfarads The transistors26, 28 and 30 are NPNtype, transistors, Model No. 2N3414.

What'is claimed is: 1. An electrical elevator call control system whichI provides command output signals to 'a controlled device comprising, incombination,

means for generating a first signal, signal stretching means connectedto said first signal generating means, said stretching means beingresponsive to said first signal generating meansfor generating a secondsignal having a duration greater than said first signal,

a commandrelay means for providing an output signal to said controlleddevice,

means connected to said relay and to said stretching means forenergizing said relay in response to said second signal and interlockmeans for said command relaymeans en- I gageable upon energization ofsaid command relay means to retain energization of said command relayand disengageable by feedback control means from said controlled.device. 7 a v v 2. The system asset forth in claim 1 including thresholdmeans for preventing operation of said relay energizing means until saidsecond signal exceeds a predetermined level such that spurious linesignals below said predetermined level'will not accidentally energizesaid relay.

3. The system of claim 1 wherein said signal stretching means includesan energy storage device having an input charging impedance and an'output discharging impedance greater than said input charging impedance,

said energy storage device being connected between said first signalgenerating means and said relay energizing means. I I

4. The system of claim 1 whereinsaid feedback control means comprisecircuit breaker meansin'series with said relay, said circuit breakermeans being operative in response to said controlled device.

5. The system of claim l wherein said components are direct currentresponsive.

6. The system of claim 1 including a plurality of said.

systems, each one of said systems being associated with a separatecommand station.'

10. An electrical elevator call control system which provides commandoutput signals to a controlled device comprising, in combination,

means for generating a first signal including an input, signalstretching means connected to said first signal generating means, saidstretching means being. responsive to said first signal generating meansfor generating a second signal having a duration' greater than saidfirst signal, means connected between said firstand saidsecond signalgenerating means for shorting out high frethreshold means for preventingoperation of said relay energizing means until said second signalexceeds a predetermined level such that spurious line signals I belowsaid predetermined level will not accidentally energize said relay.

12. The system of claim wherein said signal stretching means includes anenergy storage device having an input charging impedance and an outputdischarging impedance greater than said input charging impedance, saidenergy storage device being connected between said first signalgenerating means and said relay energizing means. I

13. The system as set forth in claim 10 including interlock means forsaid command relay means engageable upon energization of said commandrelay means to retain energization of said command relay anddisengageable by feedback control means from said con: trolled device.

14. The system of claim 13 wherein said feedback control means comprisecircuit breaker means in series with said relay, said circuit breakermeans being opera- 6 tive in response to said controlled device.

15, The system of claim 10 wherein said components are direct currentresponsive.

16. The system of claim 10 including a plurality of said systems, eachone of said systems being associated with a separate command station.

17. The system of claim 10 wherein said means for generating a firstsignal comprises a coil and means for inducing a voltage in said coil.

18. The system of claim 17 including a separate low amperage testcircuit in parallel with said coil.

19. An electrical elevatorcall control system which provides commandoutput signals to a controlled device comprising, in combination,

means for generating a first signal,

a low amperage test circuit in parallel with said means for generating afirst signal,

signal stretching means connected to said first signal generating means,said stretching means being responsive to said first signal generatingmeans for generating a second signal having a duration second signal.

output sig-

1. An electrical elevator call control system which provides command output signals to a controlled device comprising, in combination, means for genErating a first signal, signal stretching means connected to said first signal generating means, said stretching means being responsive to said first signal generating means for generating a second signal having a duration greater than said first signal, a command relay means for providing an output signal to said controlled device, means connected to said relay and to said stretching means for energizing said relay in response to said second signal, and interlock means for said command relay means engageable upon energization of said command relay means to retain energization of said command relay and disengageable by feedback control means from said controlled device.
 2. The system as set forth in claim 1 including threshold means for preventing operation of said relay energizing means until said second signal exceeds a predetermined level such that spurious line signals below said predetermined level will not accidentally energize said relay.
 3. The system of claim 1 wherein said signal stretching means includes an energy storage device having an input charging impedance and an output discharging impedance greater than said input charging impedance, said energy storage device being connected between said first signal generating means and said relay energizing means.
 4. The system of claim 1 wherein said feedback control means comprise circuit breaker means in series with said relay, said circuit breaker means being operative in response to said controlled device.
 5. The system of claim 1 wherein said components are direct current responsive.
 6. The system of claim 1 including a plurality of said systems, each one of said systems being associated with a separate command station.
 7. The system of claim 1 wherein said means for generating a first signal comprises a coil and means for inducing a voltage in said coil.
 8. The system of claim 7 including a separate low amperage test circuit in parallel with said coil.
 9. The system as set forth in claim 1 including means connected between said first and second signal generating means for shorting out high frequency spurious signals from the input to said first signal generator means.
 10. An electrical elevator call control system which provides command output signals to a controlled device comprising, in combination, means for generating a first signal including an input, signal stretching means connected to said first signal generating means, said stretching means being responsive to said first signal generating means for generating a second signal having a duration greater than said first signal, means connected between said first and said second signal generating means for shorting out high frequency spurious signals from the input to said means for generating a first signal, a command relay means for providing an output signal to said controlled device, and means connected to said relay and to said stretching means for energizing said relay in response to said second signal.
 11. The system as set forth in claim 10 including threshold means for preventing operation of said relay energizing means until said second signal exceeds a predetermined level such that spurious line signals below said predetermined level will not accidentally energize said relay.
 12. The system of claim 10 wherein said signal stretching means includes an energy storage device having an input charging impedance and an output discharging impedance greater than said input charging impedance, said energy storage device being connected between said first signal generating means and said relay energizing means.
 13. The system as set forth in claim 10 including interlock means for said command relay means engageable upon energization of said command relay means to retain energization of said command relay and disengageable by feedback control means from said controlled device.
 14. The system of claim 13 wherein said feedback control means comprise circuit breaker means in seriEs with said relay, said circuit breaker means being operative in response to said controlled device.
 15. The system of claim 10 wherein said components are direct current responsive.
 16. The system of claim 10 including a plurality of said systems, each one of said systems being associated with a separate command station.
 17. The system of claim 10 wherein said means for generating a first signal comprises a coil and means for inducing a voltage in said coil.
 18. The system of claim 17 including a separate low amperage test circuit in parallel with said coil.
 19. An electrical elevator call control system which provides command output signals to a controlled device comprising, in combination, means for generating a first signal, a low amperage test circuit in parallel with said means for generating a first signal, signal stretching means connected to said first signal generating means, said stretching means being responsive to said first signal generating means for generating a second signal having a duration greater than said first signal, a command relay means for providing an output signal to said controlled device, and means connected to said relay and to said stretching means for energizing said relay in response to said second signal. 